Tafsiran Keluaran 26:7: Rashi, Sforno & Rabbeinu Bahya

יריעת עזים CURTAINS OF עזים — i. e. GOATS HAIR (cf. Rashi on Exodus 25:4).

לאהל על המשכן. The purpose of what was called משכן had not been to serve as a tent, but to assure that the cherubs would be surrounding the Shechinah.

ועשית יריעות עזים לאהל על המשכן, “and you are to construct curtains of goats’ hair above the Mishkan.” The Torah had first commanded: “construct the Tabernacle out of ten curtains of twisted linen and blue and red-colored wool.” Concerning these curtains the Torah instructed that they were to be approximately 28 cubits long each. Now with the curtains made of goats’ hair, the instructions were that they were to be approximately 30 cubits long each. There were to be 10 curtains called משכן, whereas this second layer of curtains consisted of a total of 11.

לאהל על המשכן TO BE A COVERING UPON THE DWELLING — i. e. to spread them over the lower curtains (over those which had been already placed over the Tabernacle).